Ratchet-drive reduction



Nov. 19; 1929. R. o. HELGEBY 1,735,923

RATGHET DRIVE REDUCTION Filed June 2. 192a Patented Nov. 19, 1929 v UNITED STATES PATENT OFFICE.

RALPH OLAF HELGEBY, OF FLINT, MICHIGAN, ASSIGNOR TO A O SPARK PLUG GOM- PANY, OF FLINT, MICHIGAN, A COMPANY OF HTQHIGAK BA'JIGIBIIEl'Jf-D'RIVE REDUCTION v Application filed June 2,

This invention relates to mechanism for driving one member from another at a re-- duced speed ratio. The invention has been designed more particularly for use where considerable reduction is required, as for example in the case of odometers. More par.- ticularly the invention makes use of a pluralitiy of ratchet wheels and a single operating paw I The object of the invention is to secure reduction between a driving and driven member, the reducin means having maximum simplicity. To t is end the invention aims to avoid the use of interengaging gears. As a further object, the novel structure is designed to ,be quiet in operation and inexpensive in manufacture. Other objects and advantages will be apparent from a reading of the following description.

In the drawing, Figure 1 is a view of the improvement in elevation. Figure 2 is a transverse section. Figure 3 is a view in elevation of the pawl and ratchet. Figure 4 is a view also in elevation of a modified form 0 ratchet wheel.

Referring by reference characters to the drawing, numeral 10 is a drive shaft rotatably mounted in a suitable frame 12. The shaft 10 is held in position by a clip 14 which is carried by frame 12 and which is received in a V 1 slot. 16 of shaft 10, as shown in Figure 2.

On the end ofshaft 10 is an eccentric 18 upon which is ivotally mounted pawl 20.

A screw 22 or ot er suitable means is used to secure the pawl in position on the eccentric.

The pawl 20 is rovided with an aperture 24, one wall of w ich is shaped as a cam, as shown in Figure 3, and this cam shaped wall is arranged to engage and to ride upon a pin 28 held by the frame 12. A spring 30 secured in position by fastening means 32 normally presses the pawl toward the pin 28 and the ratchet wheel with which it is to engage.

Numeral 34 represents a primary ratchet wheel idly rotatable on shaft 36 secured to the frame 12. The ratchet wheel 34 is pressed against a shoulder 38 of shaft 36 by a spider spring 40, the latter engaging the ratchet wheel 34 and in abutment with frame 12. By this means suflicient friction is developed be- 1928. Serial No. 282,423.

tween the flange 38 and the wheel 34 to re sist relative movement when the pawl is lifted from the ratchet wheel by engagement with the pin 28 and while .it is being returned by the eccentric 18. Ratchet wheel 34 is provided with a number of shallow teeth 42 and at one or more redetermined intervals with dee teeth 44. t is obvious that a single deep tooth as in Fi re 3 may be used, or that two or more suc teeth 44 as suggested by Figure 4 may be used. If desired for any specific purpose the deep teeth ma be arranged out of symmetry. They may e successive teeth if that arrangement be preferred.

There is a secondary ratchet wheel 46 ad-. j acentto and coaxial with the first wheel 34,

this second wheel being alsorotatable on shaft 36. Ratchet wheel 46 is provided with teeth 42, in number the same as the teeth of ratchet-wheel 34. The outside diameter of the ratchet wheel 46 is slightly less than that of wheel 34 measured at the bottom of the shallow teeth. As shown in Figures 1 audit, ratchet wheel 46 carries a standard transfer disc 47 as is ordinarily used in odometers. Between disc 47 and the wheel 46 proper is a space 48 in which is received a bifurcated stamped ring 50. A star pinion shaft 52 provided with star pinions 56 for the successive rotation of figure wheels one of which is designated by numeral 54 may be used to hold the stamping 50 in position. Stamping 50 is formed with curve legs within space 48 to provide a resilient'means whereby wheel 46 resiliently engages flange 38. The purpose of this frictional engagement is to retain ratchet wheel 46 in fixed position except when being driven by the pawl 20. This construc-' and causes the pawl to be lifted from the ratchet teeth, t ereby avoiding wear and noise. On the forward movement the pawl will engage teeth 42 or 44. For each rotation of the shaft 10, the pawl will move ratchet wheel 34 one tooth, thereby reducing the mo tion of the drive shaft in proportion to the number of the teeth in ratchet wheel 34. As stated above there may be one or moredeep teeth 44 according to the further reduction required. Each time the pawl enters a deep tooth 44 it engages one of the teeth 42' of the secondary ratchet wheel 46 and moves that Wheel a distance of one tooth. Very great reduction is therefore easily effected without the use of gear teeth which would require there is but one deep tooth the secondwheel 46 will have been given one com lete rotation. If a reduction of 1024 to 2 be desired, two deep teeth will be provided on wheel 34 instead of one. It will be obvious that the deep teethmay be symmetrically arranged, or may be arranged as desired to secure a desired character of rotation of the second wheel 46. For example, the two deep teeth may be in sequence so that the second wheel will be moved by each of the two successive movements of the pawl and thereafter may remain at rest until the pair of deep teeth are again in position to be engaged by the pawl. It

will also be seen that more thanone wheel 34 ma be used to secure even greater reduction. vy the above constructions a very simple device has been arranged to secure very considerable reduction in drive ratio. This expedient is useful in many relations and particularly in drives for odometers. It avoids the expense of gear cutting and accuracy in assembling gear shafts.

I claim:

1. In drive reduction a plurality of adjacent coaxial ratchet wheels, one of said wheels being an idler, together with a driving pawl engaging the teethof the idler, said idler havpawl having a recess with an internal cam edge to engage said pin whereby said pawl may be lifted in its r'etrograde movement.

4. In combination, a driven rotatable shaft having an eccentric pin, a s ring pressed pawl pivotedon said pin, an i ler ratchet wheel having a plurality of teeth to be engaged by said paw at least one of said teeth being relatively deep, an adjacent coaxial ratchet wheel of lesser diameter, the diameter of the being an idler, together with a driving pawl engaging the teeth of said idler, said idler having a plurality of deep teeth whereby the pawl may engage the teeth of the adjacent ratchet wheel. I

In testimony whereof I flix my signature. RALPH I HELGEBY. 

